Bacteriophage ~29 of B. subtilis is an excellent model for studies of viral DNA packaging. The in vitro packaging system of ~29 DNA is as efficient as in vivo assembly. Models of DNA packaging can be tested and the structure of components can be determined. ~29 DNA with covalently bound gene product 3 at each terminus (')NA-gp3) is translocated in vitro into a preformed protein shell (1)rohead) by a machine that includes the prohead portal vertex (head-tail connector), the 174-base ~29-encoded prohead RNA and the ATPase gp16. The prohead, connector, pRNA and gp 16 are all overproduced from cloned genes permitting the structure of these components in sequential interactions with DNA-gp3 to be studied. Supercoiled pB~22 DNA wraps around the outside of the isolated ~29 connector. This is hypothesized to reflect the initial phase of DNA packaging. In this model, proheads should also bind supercoiled DNA and ~29 DNA-gp3 should be supercoiled as a prerequisite for packaging. The connector is composed of 12 or 13 copies of gp 10, each of which contains two cysteines, at least one of which is available for labeling. Connector/supercoiled pBIU22 complexes were labeled with Nanogold in hopes of orienting the connectors compared to the DNA. Initial results were promising, but the concentration of complexes purified after labeling was low. Further studies are planned.